Medscape – Searchable commercial collection of full-text articles from such useful sources as the National Institutes of Health and the Centers for Disease Control and Prevention.

ParentsPlace.com – Not health-only, but this commercial site contains many pages of sophisticated, reader friendly information on children’s health issues.

Medical Matrix – Physician maintained commercial database of annotated health links. Oriented toward medical professionals, but accessible to an educated lay person. A keyword search gets you to a subject index, from which you navigate to the links you want.